<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <!--Rendered using the Haskell Html Library v0.2--> <HTML ><HEAD ><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8" ><TITLE >Text.Printf</TITLE ><LINK HREF="haddock.css" REL="stylesheet" TYPE="text/css" ><SCRIPT SRC="haddock-util.js" TYPE="text/javascript" ></SCRIPT ><SCRIPT TYPE="text/javascript" >window.onload = function () {setSynopsis("mini_Text-Printf.html")};</SCRIPT ></HEAD ><BODY ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="topbar" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD ><IMG SRC="haskell_icon.gif" WIDTH="16" HEIGHT="16" ALT=" " ></TD ><TD CLASS="title" >base-4.2.0.2: Basic libraries</TD ><TD CLASS="topbut" ><A HREF="index.html" >Contents</A ></TD ><TD CLASS="topbut" ><A HREF="doc-index.html" >Index</A ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="modulebar" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD ><FONT SIZE="6" >Text.Printf</FONT ></TD ><TD ALIGN="right" ><TABLE CLASS="narrow" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="infohead" >Portability</TD ><TD CLASS="infoval" >portable</TD ></TR ><TR ><TD CLASS="infohead" >Stability</TD ><TD CLASS="infoval" >provisional</TD ></TR ><TR ><TD CLASS="infohead" >Maintainer</TD ><TD CLASS="infoval" >lennart@augustsson.net</TD ></TR ></TABLE ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section1" >Description</TD ></TR ><TR ><TD CLASS="doc" >A C printf like formatter. </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section1" >Synopsis</TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="decl" ><A HREF="#v%3Aprintf" >printf</A > :: <A HREF="Text-Printf.html#t%3APrintfType" >PrintfType</A > r => <A HREF="Data-Char.html#t%3AString" >String</A > -> r</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="#v%3AhPrintf" >hPrintf</A > :: <A HREF="Text-Printf.html#t%3AHPrintfType" >HPrintfType</A > r => <A HREF="GHC-IO-Handle.html#t%3AHandle" >Handle</A > -> <A HREF="Data-Char.html#t%3AString" >String</A > -> r</TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A HREF="#t%3APrintfType" >PrintfType</A > t </TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A HREF="#t%3AHPrintfType" >HPrintfType</A > t </TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A HREF="#t%3APrintfArg" >PrintfArg</A > a </TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A HREF="#t%3AIsChar" >IsChar</A > c </TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="section1" >Documentation</TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:printf" ><A NAME="v%3Aprintf" ></A ></A ><B >printf</B > :: <A HREF="Text-Printf.html#t%3APrintfType" >PrintfType</A > r => <A HREF="Data-Char.html#t%3AString" >String</A > -> r</TD ></TR ><TR ><TD CLASS="doc" ><P >Format a variable number of arguments with the C-style formatting string. The return value is either <TT ><A HREF="Data-Char.html#t%3AString" >String</A ></TT > or <TT >(<TT ><A HREF="System-IO.html#t%3AIO" >IO</A ></TT > a)</TT >. </P ><P >The format string consists of ordinary characters and /conversion specifications/, which specify how to format one of the arguments to printf in the output string. A conversion specification begins with the character <TT >%</TT >, followed by one or more of the following flags: </P ><PRE > - left adjust (default is right adjust) + always use a sign (+ or -) for signed conversions 0 pad with zeroes rather than spaces </PRE ><P >followed optionally by a field width: </P ><PRE > num field width * as num, but taken from argument list </PRE ><P >followed optionally by a precision: </P ><PRE > .num precision (number of decimal places) </PRE ><P >and finally, a format character: </P ><PRE > c character Char, Int, Integer, ... d decimal Char, Int, Integer, ... o octal Char, Int, Integer, ... x hexadecimal Char, Int, Integer, ... X hexadecimal Char, Int, Integer, ... u unsigned decimal Char, Int, Integer, ... f floating point Float, Double g general format float Float, Double G general format float Float, Double e exponent format float Float, Double E exponent format float Float, Double s string String </PRE ><P >Mismatch between the argument types and the format string will cause an exception to be thrown at runtime. </P ><P >Examples: </P ><PRE > > printf "%d\n" (23::Int) 23 > printf "%s %s\n" "Hello" "World" Hello World > printf "%.2f\n" pi 3.14 </PRE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><A NAME="v:hPrintf" ><A NAME="v%3AhPrintf" ></A ></A ><B >hPrintf</B > :: <A HREF="Text-Printf.html#t%3AHPrintfType" >HPrintfType</A > r => <A HREF="GHC-IO-Handle.html#t%3AHandle" >Handle</A > -> <A HREF="Data-Char.html#t%3AString" >String</A > -> r</TD ></TR ><TR ><TD CLASS="doc" >Similar to <TT ><A HREF="Text-Printf.html#v%3Aprintf" >printf</A ></TT >, except that output is via the specified <TT ><A HREF="GHC-IO-Handle.html#t%3AHandle" >Handle</A ></TT >. The return type is restricted to <TT >(<TT ><A HREF="System-IO.html#t%3AIO" >IO</A ></TT > a)</TT >. </TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A NAME="t:PrintfType" ><A NAME="t%3APrintfType" ></A ></A ><B >PrintfType</B > t </TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="ndoc" >The <TT ><A HREF="Text-Printf.html#t%3APrintfType" >PrintfType</A ></TT > class provides the variable argument magic for <TT ><A HREF="Text-Printf.html#v%3Aprintf" >printf</A ></TT >. Its implementation is intentionally not visible from this module. If you attempt to pass an argument of a type which is not an instance of this class to <TT ><A HREF="Text-Printf.html#v%3Aprintf" >printf</A ></TT > or <TT ><A HREF="Text-Printf.html#v%3AhPrintf" >hPrintf</A ></TT >, then the compiler will report it as a missing instance of <TT ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A ></TT >. </TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="section4" ><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:PrintfType')" ALT="show/hide" > Instances</TD ></TR ><TR ><TD CLASS="body" ><DIV ID="i:PrintfType" STYLE="display:block;" ><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0" ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3AIsChar" >IsChar</A > c => <A HREF="Text-Printf.html#t%3APrintfType" >PrintfType</A > [c]</TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfType" >PrintfType</A > (<A HREF="System-IO.html#t%3AIO" >IO</A > a)</TD ></TR ><TR ><TD CLASS="decl" >(<A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > a, <A HREF="Text-Printf.html#t%3APrintfType" >PrintfType</A > r) => <A HREF="Text-Printf.html#t%3APrintfType" >PrintfType</A > (a -> r)</TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A NAME="t:HPrintfType" ><A NAME="t%3AHPrintfType" ></A ></A ><B >HPrintfType</B > t </TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="ndoc" >The <TT ><A HREF="Text-Printf.html#t%3AHPrintfType" >HPrintfType</A ></TT > class provides the variable argument magic for <TT ><A HREF="Text-Printf.html#v%3AhPrintf" >hPrintf</A ></TT >. Its implementation is intentionally not visible from this module. </TD ></TR ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="section4" ><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:HPrintfType')" ALT="show/hide" > Instances</TD ></TR ><TR ><TD CLASS="body" ><DIV ID="i:HPrintfType" STYLE="display:block;" ><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0" ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3AHPrintfType" >HPrintfType</A > (<A HREF="System-IO.html#t%3AIO" >IO</A > a)</TD ></TR ><TR ><TD CLASS="decl" >(<A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > a, <A HREF="Text-Printf.html#t%3AHPrintfType" >HPrintfType</A > r) => <A HREF="Text-Printf.html#t%3AHPrintfType" >HPrintfType</A > (a -> r)</TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A NAME="t:PrintfArg" ><A NAME="t%3APrintfArg" ></A ></A ><B >PrintfArg</B > a </TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="section4" ><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:PrintfArg')" ALT="show/hide" > Instances</TD ></TR ><TR ><TD CLASS="body" ><DIV ID="i:PrintfArg" STYLE="display:block;" ><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0" ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Char.html#t%3AChar" >Char</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Prelude.html#t%3ADouble" >Double</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Prelude.html#t%3AFloat" >Float</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Int.html#t%3AInt" >Int</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Int.html#t%3AInt8" >Int8</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Int.html#t%3AInt16" >Int16</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Int.html#t%3AInt32" >Int32</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Int.html#t%3AInt64" >Int64</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Prelude.html#t%3AInteger" >Integer</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Word.html#t%3AWord" >Word</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Word.html#t%3AWord8" >Word8</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Word.html#t%3AWord16" >Word16</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Word.html#t%3AWord32" >Word32</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > <A HREF="Data-Word.html#t%3AWord64" >Word64</A ></TD ></TR ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3AIsChar" >IsChar</A > c => <A HREF="Text-Printf.html#t%3APrintfArg" >PrintfArg</A > [c]</TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="decl" ><SPAN CLASS="keyword" >class</SPAN > <A NAME="t:IsChar" ><A NAME="t%3AIsChar" ></A ></A ><B >IsChar</B > c </TD ></TR ><TR ><TD CLASS="body" ><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0" ><TR ><TD CLASS="s8" ></TD ></TR ><TR ><TD CLASS="section4" ><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:IsChar')" ALT="show/hide" > Instances</TD ></TR ><TR ><TD CLASS="body" ><DIV ID="i:IsChar" STYLE="display:block;" ><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0" ><TR ><TD CLASS="decl" ><A HREF="Text-Printf.html#t%3AIsChar" >IsChar</A > <A HREF="Data-Char.html#t%3AChar" >Char</A ></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></TD ></TR ><TR ><TD CLASS="s15" ></TD ></TR ><TR ><TD CLASS="botbar" >Produced by <A HREF="http://www.haskell.org/haddock/" >Haddock</A > version 2.6.1</TD ></TR ></TABLE ></BODY ></HTML >